This invention relates generally to particle study device and more particularly provides an improved device for delivering a predetermined amount of particulate matter into a flowing carrier sheath liquid leading to a sensing zone.
Ejecting mechanisms have been disclosed in the referenced United States patents which mechanisms operate to eject a predetermined amount of particulate matter into an electrolytic diluent leading to the sensing zone within a particle study device, preferably of the Coulter type. These ejecting mechanisms include those which had to be loaded manually with particulate matter and those which were coupled automatically to direct a predetermined amount of trapped particulate matter to a flowing sheath of diluent functioning as a carrier. The flowing sheath leads the particulate matter to a sensing zone when said mechanism is coupled thereto.
As known, where a flow sheath of carrier liquid is generated, the individual particles follow a straight line through the center of the path traveled by the sheath, the particles and the sheath traveling in distinct streams. While not uniformly spaced, the particles do travel along a straight line in an ordered fashion.
Such ejecting devices include a fine ejecting aperture of microscopic proportions leading from a reservoir carrying a volume of trapped sample to a sheath flow device. It would be desirable to seal off the said aperture during the trapping of said sample within the reservoir. If one desired to enlarge the ejecting aperture to slightly greater than microscopic proportion, undesired mixing could be a problem. Likewise the prevention of such undesired mixing has depended to a considerable extent upon the maintenance of a desired surface tension during the trapping phase. This is not always feasible. Further, when the ejecting assembly is permanently mounted to the flow sheath arrangement, sealing becomes a considerable problem which requires expensive precision in the fabrication of the shear valve action valves utilized therewith.
Thus it would be highly desirable to provide against such undesired mixing in the transport of the sample and liquids through the systems such as typified by the referenced patents.